6U CubeSat to Mars

We’ve been working on Asteroid Prospector, a 6U CubeSat to explore Near Earth Objects, for the past two years. It is quite a challenge to pack all the hardware into a 6U frame. Here is our latest design:

APExploded

CAD

The nadir face has both an Optical Navigation System camera and a JPL designed robot arm. The arm is used to grapple the asteroid and get samples. The camera is used both for interplanetary navigation and close maneuvering near the asteroid.

Our fuel load only allows for one way missions but could be increased for sample return missions by adding another xenon tank, making it more of a 12U CubeSat. With that in mind, we wondered if we could do a Mars orbital mission with our 6U. It turns out it is possible! We would start in a GPS orbit, carried there by one of the many GPS launches. The spacecraft would spiral out of Earth orbit and perform a Hohmann transfer to Mars. Even though we are using a low-thrust ion engine, the burn duration is a small fraction of the Hohmann ellipse time making a Hohmann transfer a good approximation. We then spiral into Mars orbit for the science mission as seen in a VisualCommander simulation.

SimSummary

The low cost of the 6U mission makes it possible to send several spacecraft to Mars, each with its own instrument. This has the added benefit of reducing program risk as the loss of one spacecraft would not end the mission. Many challenges remain, including making the electronics sufficiently radiation hard for the interplanetary and Mars orbit environments. The lifetime of the mechanical components, such as reaction wheels, must also be long enough to last for the duration of the mission.

We’ll keep you posted in future blogs on our progress! Stay tuned!

PSS featured on Time.com

Only two days after a visit by journalist Michael Lemonick, our DFD fusion drive was featured in his post on Time.com’s science section!

Going to Mars via Fusion Power

The article does misstate that Sam Cohen is a PSS engineer, when in fact he is the lead researcher on the PFRC at Princeton Plasma Physics Lab (PPPL). The proposed NASA mission to the Jupiter Icy Moons was JIMO – Jupiter Icy Moon Orbiter Mission. JUICE JUpiter ICy moon Explorer is a European Space Agency mission.

For more information on DFD, go to our fusion propulsion page.

Direct Fusion Drive

Direct Fusion Drive Mars Mission – Deep Space Habitat

Check out our new banner! We modified our spacecraft to use NASA’s Deep Space Habitat:

 

 

 

 

 

 

Image Source: NASASpaceFlight

The habitat has a 500 day configuration, with more than enough room for all of the astronauts and their supplies!

http://www.nasaspaceflight.com/2012/03/dsh-module-concepts-outlined-beo-exploration/
http://www.nasaspaceflight.com/2012/04/delving-deeper-dsh-configurations-support-craft/

We will use the Orion spacecraft for transfer from Earth’s surface to Earth orbit, where it will dock with the DFD powered spacecraft.  That is what the banner image is portraying! Once the astronauts are aboard the DFD powered spacecraft, they will travel to Mars and back in roughly 10 months, including a 1 month stay at Mars.  After they have returned to Earth orbit, the spacecraft will dock with the Orion capsule. The crew can then safely return to Earth’s surface aboard the Orion!

Twenty-Four People

That is the number of people in the entire history of human civilization who have left Low Earth Orbit (LEO).  You heard me right, only 24 people (all Apollo astronauts) have left the protection of Earth’s magnetic field.  The prospects of journeying past LEO is a daunting one.  There is dangerous radiation in deep space that the magnetic field protects us from.

There are two types of radiation that pose a risk to astronauts: those that originate outside the solar system, the Galactic Cosmic Rays (GCR), and those that come from the sun, called Solar Proton Events (SPE).  The GCR consist mainly of heavy atomic nuclei, while the SPE, as the name suggests, consists mostly of protons.  Both of these types of radiation are high energy, so if they hit an unshielded astronaut they could cause damage to DNA, cell replication, and even lead to cell death.

The SPE, released during solar flares and coronal mass ejections, are especially dangerous as they emit so much radiation that it could be fatal to an unprotected astronaut.  Luckily SPEs are rare and none occurred during the Apollo missions.  Most of the damage from radiation is from prolonged exposure to it, which increases an astronaut’s risk of developing problems such as cancer and cataracts.

Radiation is not the only danger to astronauts on a deep space mission, though.  On a long mission, such as our proposed 308 day DFD powered mission to Mars, the extended period in weightlessness can cause issues as well.  Bones and muscles that normally have to deal with gravity suddenly do not have any load on them.  For this reason astronaut’s bones and muscles (including the heart!) begin to atrophy and lose mass.  The ones most affected are those that fight with gravity: the bones and muscles in the lower back and legs.

Astronaut Ken Bowersox runs on a treadmill using a loading harness.

Image Source: NASA
http://spinoff.nasa.gov/Spinoff2009/hm_5.html 

Astronauts will need to exercise daily to minimize these losses, but even that will not be 100% effective.  Similarly there will be radiation shielding on the spacecraft and a storm shelter for the SPE, but nothing is perfect.  These are just some of the risks associated with a voyage to Mars.  Despite the risks, I do not think we will have any problems finding volunteers to be number 25!

Human Missions To Mars

You may have noticed that we have a new banner image of our Direct Fusion Drive (DFD) transfer vehicle with the Orion spacecraft.

http://www.nasa.gov/exploration/systems/mpcv/index.html

This is because we have been able to shrink the spacecraft so that it fits on top of a single NASA Space Launch System (SLS)

http://www.nasa.gov/exploration/systems/sls/

Evolved Configuration launcher which can launch up to 130 metric tons into low earth orbit! The first mission would be to orbit Mars for a few days and then return to Earth. The vehicle would remain in orbit around the Earth. The next SLS launch would bring up a second transfer stage with the lander. A third launch would bring up another Orion and the crew for the landing mission.

The DFD transfer vehicles stay in low-earth orbit where they can be used for a variety of missions, such as deflecting asteroids or lunar missions.

We are currently working on the mission design along with conceptual designs of the transfer vehicle and Mars lander. A key consideration in the mission plan is keeping the astronauts healthy so astronaut physiology is a key part of our research.

Our colleagues at the Princeton Plasma Physics Laboratory

http://www.pppl.gov

are running two experiments that support DFD. One is PFRC-2, Princeton Field Reversed Configuration 2, which is testing the reactor core. Here you see the experiment in action!

PFRC2

and MNX which is studying magnetic nozzles. We have two more test reactors planned, PFRC-3 and PFRC-4. The last will burn deuterium and helium-3 to produce fusion power. After that we will be ready to build a space version of the fusion propulsion system.

Of course, this reactor could be used for terrestrial power generation. In future posts we’ll talk about sources of helium-3 and alternative fuels that could power this reactor.